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| author | Nicolas Maier <nicolas.maier.dev@gmail.com> | 2024-01-20 09:10:18 +0100 |
|---|---|---|
| committer | Marc Kleine-Budde <mkl@pengutronix.de> | 2024-02-12 16:55:17 +0100 |
| commit | fec846fa7eddf7bb651bf88bd78c7db1410ae3b1 (patch) | |
| tree | 4e8d090eb94914f01777cd65420040a14f69d6ae /Documentation/networking/can.rst | |
| parent | 970cb1ceda170a3e583a5f26afdbebdfe5bf5a80 (diff) | |
can: bcm: add recvmsg flags for own, local and remote traffic
CAN RAW sockets allow userspace to tell if a received CAN frame comes
from the same socket, another socket on the same host, or another host.
See commit 1e55659ce6dd ("can-raw: add msg_flags to distinguish local
traffic"). However, this feature is missing in CAN BCM sockets.
Add the same feature to CAN BCM sockets. When reading a received frame
(opcode RX_CHANGED) using recvmsg, two flags in msg->msg_flags may be
set following the previous convention (from CAN RAW), to distinguish
between 'own', 'local' and 'remote' CAN traffic.
Update the documentation to reflect this change.
Signed-off-by: Nicolas Maier <nicolas.maier.dev@gmail.com>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Link: https://lore.kernel.org/all/20240120081018.2319-1-socketcan@hartkopp.net
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Diffstat (limited to 'Documentation/networking/can.rst')
| -rw-r--r-- | Documentation/networking/can.rst | 34 |
1 files changed, 18 insertions, 16 deletions
diff --git a/Documentation/networking/can.rst b/Documentation/networking/can.rst index d7e1ada905b2..62519d38c58b 100644 --- a/Documentation/networking/can.rst +++ b/Documentation/networking/can.rst @@ -444,6 +444,24 @@ definitions are specified for CAN specific MTUs in include/linux/can.h: #define CANFD_MTU (sizeof(struct canfd_frame)) == 72 => CAN FD frame +Returned Message Flags +---------------------- + +When using the system call recvmsg(2) on a RAW or a BCM socket, the +msg->msg_flags field may contain the following flags: + +MSG_DONTROUTE: + set when the received frame was created on the local host. + +MSG_CONFIRM: + set when the frame was sent via the socket it is received on. + This flag can be interpreted as a 'transmission confirmation' when the + CAN driver supports the echo of frames on driver level, see + :ref:`socketcan-local-loopback1` and :ref:`socketcan-local-loopback2`. + (Note: In order to receive such messages on a RAW socket, + CAN_RAW_RECV_OWN_MSGS must be set.) + + .. _socketcan-raw-sockets: RAW Protocol Sockets with can_filters (SOCK_RAW) @@ -693,22 +711,6 @@ where the CAN_INV_FILTER flag is set in order to notch single CAN IDs or CAN ID ranges from the incoming traffic. -RAW Socket Returned Message Flags -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -When using recvmsg() call, the msg->msg_flags may contain following flags: - -MSG_DONTROUTE: - set when the received frame was created on the local host. - -MSG_CONFIRM: - set when the frame was sent via the socket it is received on. - This flag can be interpreted as a 'transmission confirmation' when the - CAN driver supports the echo of frames on driver level, see - :ref:`socketcan-local-loopback1` and :ref:`socketcan-local-loopback2`. - In order to receive such messages, CAN_RAW_RECV_OWN_MSGS must be set. - - Broadcast Manager Protocol Sockets (SOCK_DGRAM) ----------------------------------------------- |